Knowth
Knowth is a Neolithic passage tomb complex near Drogheda, in County Meath, built around 3200 BC above the River Boyne: a large mound ringed by 17 smaller tombs, with the largest group of megalithic art in Europe. Part of the Brú na Bóinne World Heritage Site, it is reached only on guided tours from the visitor centre at Donore, and its chambers are not open.
